According to western tradition, the left hand shows the luck God gave you, so in the western countries, the ring is usually worn on the left hand. Not wearing a ring means being single. Western early medicine that the left ring finger in the hands of ten fingers in the distance with the heart of the recent, so will represent the marriage ring on the left ring finger, and then reflect the sacred status of love, and spread so far.
Simple memory method, in fact very good to remember, four words, heat detoxification.
index finger, middle finger, ring finger, small finger in turn is green (year), Hot (Love), Knot (marriage), Alone (body).